The invention relates to a photographing apparatus, and more particularly, to a photographing apparatus on which either an automatic or a manual film winding mechanism may be mounted.
In a known photographing apparatus for use with microscopes in which either an automatic or a manual film winding mechanism can be mounted, it is necessary to discern the type of film winding mechanism, either automatic or manual, which is mounted on the photographing apparatus. By way of example, when a film winding assembly is mounted which utilizes an automatic film winding mechanism, there is provided means for detecting a film end, thereby preventing a shutter release from occurring whenever the film end is detected. Such detection means may comprise a rotary disc connected with a motor shaft associated with the film winding mechanism and having a notch formed therein so that the angular position of the notch may be detected by a mechanical arm to thereby operate a switch. In such an arrangement, a length of the film corresponding to one frame is wound up during one revolution of the motor shaft. Assuming that the arm moves into the notch to turn the switch off after one frame of the film has been wound up, the motor will be energized for a given time interval in response to a next wind-up command signal, whereby the arm will be moved out of the notch to turn the switch on. When the motor has substantially completed one revolution, the arm will again move into the notch to turn the switch off. As long as the switch is turned on and off in a sequential manner (off-on-off), there is an available length of the film, enabling a subsequent film winding operation. The film end will be reached principally in two manners. First, the available length of the film may have been precisely exhausted during a previous winding operation. In this instance, the motor shaft cannot rotate even though the motor is energized, and hence the switch remains off. Alternatively, if the film end is reached during the course of a film winding operation, the switch remains on. The condition that the switch remains off or on can be detected as an indication of the fact that the film end is reached, thereby inhibiting a subsequent photographing operation or issuing an alarm to the user. However, it is possible, though with a very low probability, that a very small length of the film remains available at the termination of a previous film winding operation, and hence the rotary disc is permitted to rotate through a small angle, whereupon the arm is driven out of the notch. However, when the motor is deenergized, the rotary disc will reverse slightly by reaction, whereby the arm is again allowed to move into the notch. In this instance, the switch will cycle through off-on-off, making it difficult to distinguish such operation from a normal film winding operation. This may cause malfunctioning of the arrangement.
When a winding assembly which utilizes a manual film winding mechanism is mounted on the photographing apparatus, there is no provision of the motor and the detecting means which detect the angular position, both mentioned above. As a result, a signal, which is equivalent to the switch output maintained at off level, is supplied to a decision circuit, which may inadvertently light a film end warning lamp or disables a second and subsequent release operation even though an initial release operation is enabled. These difficulties can be avoided by providing a changeover switch on an operating panel of the control box which assumes positions corresponding to an automatic and a manual film winding operation. However, with this arrangement, it is necessary that a user operate the switch every time the type of the film winding assembly used is changed from a previous one, adding troublesome work. In addition, the operation of the changeover switch may inadvertently be forgotten, missing a chance to take a picture. This will be of a greater significance when taking a picture with a microscope. In particular, a microscope requires a number of operations, which may increase the likelihood that the operation of the changeover switch may be forgotten.